JOEL - At present time there are absolutly no restrictions for any worthy male member of the Mormon Church to hold priesthood authority and serve in leadership positions, regardless of their race. Whereever you go in the world, the native members of the Church do now serve in important leadership positions for thier own countrymen. There are African bishops in Africa, Japanese bishops in Japan, Chinese bishops in Hong Kong China, etc.
Part of the reason there are not many "of color" (black) in leadership positions at the higher levels(General Authorities), is because of the small percentage of black members (about 3-4%) that are in the church today. Also, before 1978, blacks of African decent were not allowed to hold the priesthood that was needed in order to serve in leadership positions (For more information on the reason for this go here).